[Experimental studies for botulinum toxin type A on allergic rhinitis in the rat].

OBJECTIVE: To study the effect of botulinum toxin-A on inhibiting rhinorrhea, on expression of VIP at nasal mucosa, on morphometrical change with an immunohistochemical and histological methods in rats allergic rhinitis. METHODS: Ovalbumin sensitized the rat as animal model of allergic rhinitis. Animals were divided into control group (n = 8), allergic group (n = 12), allergic animal treated by BTX-A group (n = 6). VIP immunoreactivity at nasal mucosa in the rat allergic rhinitis was studied by immunohistochemical. The morphometrical changes at nasal mucosa were observed by histological staining methods. RESULTS: The results showed that the symptoms of allergic rhinitis, nasal rhinorrhea and sneezing, were remarkably relieved after ovalbumin application in the rat. The nasal rhinorrhea symptom diminished after BTX-A treated. The quantity of nasal secretion were significantly reduced(P < 0.05) in allergic one treated by BTX-A group as compared with allergic group. Hematoxylin and eosin staining demonstrated that no edema, small vessels were found in the nasal mucosa and after BTX-A treatment, but edema, vasodilational and inflammational cell infiltration were observed in the allergic group. Immunohistochemical study revealed that VIP immunoreactive fibers in the nasal mucosa showed a marked decrease after BTX-A application, but the density and a large number of VIP fibers were significantly found in the allergic group. CONCLUSION: The results suggested that local BTX-A treatment was a selective and non-traumatic method to reduce a long lasting desensitization of the nasal mucosa, to alleviate nasal congestion, rhinorrhea and sneezing, and to reduce the sensory neuron sensitivity of the mucosa.